从人员列表中提取名称列表

给定 Person 结构

struct Person {
    let name: String
    let birthYear: Int?
}

和一个 Person(s) 阵列

let persons = [
    Person(name: "Walter White", birthYear: 1959),
    Person(name: "Jesse Pinkman", birthYear: 1984),
    Person(name: "Skyler White", birthYear: 1970),
    Person(name: "Saul Goodman", birthYear: nil)
]

我们可以检索包含每个 Person 的 name 属性的 String 数组。

let names = persons.map { $0.name }
// ["Walter White", "Jesse Pinkman", "Skyler White", "Saul Goodman"]